1. Field of the Invention
The present invention relates to a process for producing a photosensitive material capable of forming full color images, and more specifically, to a process for producing such material in a single batch.
2. Description of the Prior Art
Imaging systems employing photosensitive microcapsules are described in U.S. Pat. Nos. 4,399,209 and 4,440,846, assigned to The Mead Corporation. These patents teach the formation of images by the exposure-controlled release of an image-forming agent from a microcapsule containing a photohardenable composition. The image-forming agent is typically a substantially colorless color precursor which reacts with a developer to form a visible image.
U.S. patent application Ser. No. 339,917, filed Jan. 18, 1982 (corresponding to U.K. Pat. No. 2,113,860), and U.S. Pat. No. 4,576,891 disclose a full color imaging system wherein three sets of microcapsules which are sensitive to different bands of actinic radiation are employed. These microcapsules respectively contain cyan, magenta and yellow color precursors.
Panchromatic, full color, imaging systems wherein a panchromatic imaging sheet is exposed to visible light and subsequently developed are described in European Application No. 0233567.
To produce the full color imaging systems described above, three sets of microcapsules containing respectively cyan, magenta and yellow color precursors have independently been formed, mixed together, and coated onto a substrate. The three sets of capsules are mixed in amounts such that the combination of the three produces a neutral black image when developed. See, for example, Example 4, U.S. Pat. No. 4,576,891.
Although the above-described inventions have significantly advanced imaging technology, the inventions still suffer from minor drawbacks. For example, when producing a full color photosensitive material according to the prior art teachings, three independent batches of microcapsules, each batch containing a specific color former and a specific photosensitive composition must be prepared, filtered, and subsequently mixed together to form the photosensitive coating composition. As a result, independent storage facilities for containing each of the different color-forming microcapsules must be maintained and plant mixing and filtration equipment must be cleaned between each capsule batch preparation or separate manufacturing facilities must be maintained. Furthermore, increased processing costs result because of the numerous manufacturing steps involved. Moreover, the requirement of preparing three independent batches of microcapsules before forming the photosensitive composition causes the composition to be more susceptible to instability as a result of potential contamination to any of the independent microcapsule batches. Contamination to any of the batches can be caused by, for example, contaminated process equipment.
Accordingly, there exists a need in the art for improved methods for producing photosensitive microcapsule compositions capable of forming full color images.